Effect of bremsstrahlung radiation from accelerated electrons on the structure and surface morphology of low-density polyethylene

A comprehensive study of the structural and morphological changes in low-density polyethylene induced by bremsstrahlung irradiation in the dose range of 0–900[Formula: see text]kGy is presented. The observed effects are compared with those resulting from Co-60 gamma irradiation. The novelty of this work lies in the identification of specific features of structural modifications occurring in the near-surface layer of low-density polyethylene under bremsstrahlung irradiation with a continuous energy spectrum (with a maximum energy up to 4.5[Formula: see text]MeV), applied for polymer modification. It is shown that at a dose of 100[Formula: see text]kGy, the degree of crystallinity increases from [Formula: see text] to [Formula: see text], indicating the predominance of radiation-induced structural ordering processes. With a further increase in dose up to 900[Formula: see text]kGy, the crystallinity decreases to [Formula: see text]. At the same time, new bands appear in the Raman spectra at [Formula: see text]1672 and [Formula: see text]1720[Formula: see text]cm[Formula: see text], corresponding to the formation of carbon–carbon double bonds and carbonyl groups, which indicate the dominance of degradation and oxidative processes. The study of surface microrelief reveals smoothing effects at high doses. The average surface roughness ([Formula: see text]) changes from [Formula: see text] to [Formula: see text] [Formula: see text]nm ([Formula: see text]400[Formula: see text]kGy), followed by a decrease to [Formula: see text] [Formula: see text]nm ([Formula: see text]900[Formula: see text]kGy). Comparison with gamma irradiation results demonstrates the specific nature of bremsstrahlung effects, associated with its continuous energy spectrum and the near-surface character of energy absorption, leading to the formation of inhomogeneous structural modifications in the surface layer.

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